Gas plating of alloys



United States Patent GAS PLATING 0F ALLOYS Elmer Robert Breining,Dayton, Ohio, assignor, by mesne assignments, to Union CarbideCorporation, New York, N.Y., a corporation of New York Filed Nov. 7,1958, Ser. No. 772,519

11 Claims. (Cl. 117-106) This invention relates to the formation ofalloys and particularly to phosphorous containing alloys such as thoseof nickel and iron.

Nickel-phosphorous alloys and to a lesser extent ironphosphorous alloysfind utility in a variety of applications. For example, nickelcontaining Ni3P is relatively easily soldered, below 750 F. has goodhardness characteristics and may be chrome plated for decorativeapplications. Such alloys are useful for example in electricalconnectors, aircraft parts and the like. Further, bonding to othermetals such as stainless steel, aluminum, nickel, copper and magnesiumis advantageously achieved.

It is a primary object of this invention to describe a novel method forthe attainment of alloys containing a base metal and a combination ofthe base metal with phosphorous.

Another object of the invention is to describe a process for theproduction of phosphorous containing alloys having a high degree ofpurity.

A particular object of the invention is the provision of an alloy ofnickel phosphorous or iron phosphorous achieved by deposition of thecomponents from the gaseous state.

In the practice'of the invention a volatile phosphorous component suchas phosphine, phosphorous itself, or organic phosphorous compounds, suchas the alkyl and aryl, is volatilized. Nickel carbonyl or othervolatilizable, heat decomposable metal bearing compound is present to areaction chamber with the volatilized phosphorous component. Thereaction chamber contains an object upon which a lm of the alloy is tobe deposited and this object is suitably heated to eifect decompositionof the gases.

The decomposition of the metal bearing gas in the case of nickelcarbonyl provides nickel as the base metal; iron pentacarbonyl providesiron as the base metal.

Simultaneous co-deposition of the phosphorous component and the metalbearing gas provide on the heated object the alloy. Speciliccharacteristics in the alloy are attained by combining more or less ofthe phosphorous component with the metal bearing component in thegaseous state. In the case of nickel carbonyl and trimethyl phosphinethe alloy desired contains nickel metal and NisP. The content of Ni3Pcontrols the ultimate properties -of the product and the Ni3P isdispersed throughout the nickel phase.

Tri-methyl phosphine is a preferred source of the phosphorous as it hasa boiling point close to that of nickel carbonyl and volatilization ismore readily controllable than with phosphine, for example, where highreaction temperatures are required due to the stability of thephosphine.

Tri-ethyl phosphine which has a higher boiling point is more suitablewhen iron pentacarbonyl is employed. However, methyl di-ethyl phosphine,methyl ethyl propyl phosphine and others though somewhat more expensivepresently, will serve the purpose.

The alloy deposition rate is a function of the flow rate of thephosphorous and base metal components, the temperature of the articlebeing plated and to some extent the area of the object and the size ofthe plating chamber. Deposition rate of 2 to l0 mils per hour arepracticable while thickness may be from 0.1 mil to l0 mils or more.

The flow sheet illustrates the essential steps of the process.

As will be noted from the flow sheet a liquid phosphorous containingcomponent and a liquid metal bearing component are passed to a flashvaporizer and then to a reaction chamber wherein the heated object iscontained. If desired a carrier gas, such as nitrogen, argon or carbondioxide may be utilized to aid the flow of the vaporized materials tothe reaction chamber. Within the reaction chamber the mixed gasescontact the heated object and deposit thereon, forming a coating of thealloy.

As a specific example, liquid tri-methyl phosphine and nickel carbonylare metered separately to a common ash vaporizer along with the flow ofcarrier gas and are As exemplary of the use of iron pentacarbonyl forthe formation of an alloy containing iron and iron phosphorous thefollowing data are applicable:

Sample area square inches 10 Substrate Steel Tri-ethyl phosphine, liquidcc./min 2.5-10 Iron pentacarbonyl, liquid cc./min 2-4 (Optional) carbondioxide cc./min 400-850 Vaporizer temperature F 260-285 Substratetemperature F 400-800 Phosphorous content of deposit (Fe3P and Fe2P inan iron matrix) percent 2-14 Nickel do 9'8-86 Copper may be substitutedfor the steel substrate in the foregoing samples.

The phosphines, particularly the alkyl phosphines and the arylphosphines, are available and many have characteristics which wouldrender them suitable, such as butyl phosphine and di-butyl phosphine, aswell as cyclohexyl phosphine and phenyl phosphine, also alkyl halidephosphorous compounds have properties indicating utility in the process.

It will be understood that this invention is susceptible to modificationin order to adapt it to diiferent usages and conditions and accordingly,it is desired to comprehend such modifications within this invention asmay fall within the scope of the appended claims.

What is claimed is:

1. The process of alloy formation 'which comprises combining in thevapor state a volume of a heat decomposable phosphorous component and aVolume of a heat decomposable metal bearing gas, and contacting anobject heated to the decomposition temperature of the combined vapors toeffect deposition of a phosphorous containing alloy on the object.

2. The process of alloy formation which comprises combining in the vaporstate a Volume of a heat decomposable phosphorous component and a volumeof gaseous nickel carbonyl, and contacting an object heated to thedecomposition temperature of the combined vapors to effect deposition ofa phosphorous-nickel alloy on the object.

3. The process of alloy formation which comprises combining in the vaporstate a volume of a heat decomposa'ble phosphorous component and avolume iron pentacarbonyl, and contacting an object heated to thedecomposition temperature of the combined vapors to elect deposition ofa phosphorous-iron alloy on the object.

4. The process of alloy formation which comprises the steps of combiningin the vapor state a volume of tri-methyl phosphine and a volume ofgaseous nickel carbonyl, and contacting an object heated to thedecomposition temperatures of the vapors to eifect deposition o-f aphosphorous-nickel alloy on the object.

5. The process of alloy formation which comprises the steps of combiningin the vapor state a volume of triethyl phosphine and a volume ofgaseous iron pentacarbonyl, and contacting an object heated to thedecompositio-n temperature of the combined vapors to effect depositionof a phosphorous-iron alloy on the object.

6. The process of alloy formation which comprises the steps of passingto a vaporizer a liquid phosphorous cornponent and a liquid heatdecomposable metal bearing compound to effect vaporization of thecomponent and compound, combining the vapors of the component andcompound, and contacting an object heated to the decompositiontemperature of the combined vapors to effect deposition of a phosphorouscontaining alloy on the object.

7. The process of alloy formation which comprises the steps of meteringliquid trimethyl phosphine and liquid nickel carbonyl to a vaporizer toeffect vaporization of the phosphine and carbonyl, combining the vaporsof the carbonyl and phosphine in one atmopshere, and contacting anobject heated to the decomposition temperature of the carbonyl andphosphine to effect deposition of a phosphorous-nickel alloy on theobject.

8. The process of alloy formation which comprises the steps of meteringliquid triethyl phosphine and liquid iron pentacarbonyl to a vaporizerto elfect vaporization of the phosphine and pentacarbonyl, combining thevapors of the carbonyl and phosphine in one atmosphere, and contactingan object heated to the decomposition temperature of the carbonyl andphosphine to effect deposition of a phosphorous-iron alloy on theobject.

9. The process of alloy formation which comprises the steps ofvaporizing tri-methyl phosphine and nickel carbonyl at a temperatures ofbetween 112 F. and 170 F., combining the vapors in a common atmospherewith an object heated to between 350 F. and 700 F. to thereby decomposethe phosphine and carbonyl together to deposit an alloy ofnickel-phosphorous on the object.

l0. The process of alloy formation which comprises the steps ofvaporizing tri-ethyl phosphine and iron pentacarbonyl at a temperatureof between 260 F. and 285 F., combining the vapors in a commonatmosphere with an object heated to between 400 F. and 800 F. to therebydecompose the phosphine and pentacarbonyl together to deposit an alloyof iron-phosphorousl on the object.

11. The process of alloy formation which comprises the steps ofvaporizing tri-methyl phosphine and nickel carbonyl, combining thevaporized phosphine and carbonyl in one atmosphere, providing an objectheated to the decomposition tempertaure of the carbonyl and phosphine,and directing the combined phosphine and carbonyl atmosphere with acarrier gas into contact with the heated obiect to thereby effectdeposition of a nickelphosphorous alloy on the object.

References Cited in the le of this patent UNITED STATES PATENTS2,041,493 Schlecht et al. May 19, 1936 FOREIGN PATENTS 376,652 GermanyJune 4, 1923 OTHER REFERENCES Zeitschrift fr Anorganishe Chemie, vol.238 (1938), pages 72 and 73.

1. THE PROCESS OF ALLOY FORMATION WHICH COMPRISES COMBINING IN THE VAPORSTATE A VOLUME OF HEAT DECOMPOSABLE PHOSPHOROUS COMPONENT AND VOLUME OFA HEAT DECOMPOSABLE METAL BEARING GAS, AND CONTACTING AND OBJECT HEATEDTO THE DECOMPOSITION TEMPERATURE OF THE COMBINED VAPORS TO EFFECTDEPOSITION OF A PHOSPHOROUS CONTAINING ALLOY ON THE OBJECT.